There are numerous ways and reasons to access a patient's vasculature. Patients may need administration of IV therapy for hydration, antibiotics, other medications, chemotherapy, blood products, and the like. The type of vascular access device will depend on the patient, diagnosis length of time needed, lifestyle, healthcare worker's preference, patient's ability and preference, what the device is being used for, and difficulties relating to using or maintaining the device.
Some peripheral IV devices provide access through a skin opening using a cannula-over-needle assembly, in which a flexible plastic cannula is slidably mounted over a metal introducer needle. After the tip of the introducer needle and cannula are positioned into the patient's targeted blood vessel via venipuncture, the tip of the cannula is advanced inside the vessel over the needle to the appropriate position and secured. The introducer needle is then withdrawn and discarded while the flexible cannula is retained in its position to provide fluid communication with the targeted vessel. In some emergency treatment circumstances, blood may seep from the vessel, through the cannula, and possibly out of the proximal end of the access device (after the introducer needle is withdrawn). A user may reduce the likelihood of such blood seepage by applying finger pressure (with a first hand of the user) to the patient's skin near the targeted vessel (e.g., a tamponade) until a secondary instrument can be assembled to the proximal end of the access device (using a second hand of the user).